Knock-resistant motor fuel



Da@ 13, i945. D. R. cARMoDY 4 xNocxjREsIsTANT MOTOR FUEL Filed June 19, 1943 WBYNNMK mm,

Patented Dee 1s, 194s 2,391,034 xNocx-aasrsrm Moron FUEL Don R. Carmody, Newton, Iowa, assignor to Standard i! Company, Chi

ration of Indiana caso, lll, a com- Applioatlon June 19, 1943, Serial No. 491,487

Claims This invention relates to a process of making motor fuels and particularly high knock rating motor fuel such as aviation gasoline engine fuel,

wherein fuels of high knock rating command a high premium. One object of the invention is vto produce aviation fuel from hydrocarbon gases and methanol by a combined process of alkylation and etherization. Another object of the invention is to provide an aviation fuel containing both hydrocarbon alkylates and methyl tertiary butyl ether as the principal constituent. Another object of the invention is to carry out an alkylation process with a mixture of hydrocarbon gases commercially available from the cracking of heavy oils and removing therefrom the isobutylene.

perature-controlling means (not shown), a cooler generally being required in the case ofthe alkyla- -tor and a heater in the case of the etherizer.

Heat may also be supplied to the etherizer by introducing methanol in the form of heated vapors, or by heating the hydrocarbon stream introduced by line I8.

From the ether-iger I6 reaction products are withdrawn by line 2li leading to neutralizer 2l in which the products are contacted with a solution of sodium hydroxide, sodium carbonate or other suitable alkaline material. From neutralizer 2| thereby diminishing polymerization and providing to 100 percent, and generally about 95 to 98 percent, is introduced by line Il into alkylator Ii. Simultaneously there is introduced into the alkylator by lines I2 and I3 liquefied hydrocarbonv gases hereinafter described. The alkylator II is maintained under sumcient pressure, generally of the order of 100 to 200 pounds per square inch,

to maintain thehydrocarbons in liquid condition. The alkylation reaction is conducted at a temperature in the range of about to 1509 F., preferably about 50 to 100 F. 'A high degree of agitation is provided by mechanical agitator I4.

Spent acid from the alkylator is conducted by line I5 continuously or intermittently to etherizer I6, also provided with a 'suitable agitator Il. Methanol is charged to the etherizer by line Il and isobutylene-containing hydrocarbons by line I9. The etherization reaction is conducted at a temperature in the range of about 100 to 275 F.,-

preferably at about 150 F. Suiiicient pressure is. employed to maintain the hydrocarbon gases and the reaction products in the liquid phase.

is maintained inthe range of about 30 to 85 percent and preferably about 65 to 'I5 percent, the concentration of '70 percent H2804 based on the s, acid phase.beingsatisi'actory. The temperature of both alkylator and etherizer may be controlled by recycling the contents through external temthe neutralized reaction products are conducted by line 22 to debutanizer 23 whereinCl hydrocarbons and lighter products are withdrawn at the top by line 24 leading to fractionator 25, the principal function of which is tolseparate dimethyl ether from C4 hydrocarbons. The dimethyl ether vapors are discharged by line.26 and may be withdrawn as a by-product of the process. However, it is preferred to condense the dimethyl'ether in condenser 21 and receiver 2s whence the ether is conducted by line 28 back to etherizer I6, wherein it'replaces part of the methanol used in etherizing isobutylene. f

The C4 hydrocarbons are withdrawn from the `base of fractionator 25 by line 30 and pump 3| whence they are introduced to alkylator II by line I3. If desired, this fraction may be further separated into normal butane and isobutane, only the latter being recycled to alkylator I I.

Feed stock supplied to etherizer I8 may be commercially pure isobutylene or preferably an unsaturated C4 hydrocarbon fraction obtained fromrthe cracking of petroleum or from the dehydrogenation of a C4 petroleum fraction. This unsaturated C4 feed stock usually contains normal butane and isobutane as well as normal butylene and isobutylene. Because of the greater speed of the reaction between methanol and isobutylene, the isobutylene is preferentially etherized in reactor II. Substantially complete etherization of isobutylene may be obtainedby em- The concentration of sulfuric acid inthe etherizer s ploying an excess of methanol. In this case provision may be made for recovering excess methanol from the reaction products by -water washing, or it may be allowed to remain in the finished aviation fuel. In general, I prefer to employ about equimolecular amounts of methanol and isobutylene, in which case a small but unimportant amount of isobutylene will be polymerized in etherizer Il and the remainder will be carried over to the-alkyiator through fractionators Il and 2l by line Il ashereinabovedescribed. The remaining Ct hydrocarbons pass through the the high knock rating of methyl tertiary butyl m ether.

Unsaturated hydrocarbons are supplied to alkylato II by line I2 and for this purpose I mayuse propylene, butylene or amylene, or a mixed hydrocarbon gas fraction from the cracking of vpetroleum or the dehydrogenation of petroleum 15 gases. A C4 fraction identical with that supplied to etherizer I6 by line Il is suitable. If desired, commercially available imsaturated C4 hydrocarbon mixtures may be carefully fractionated to remove the isobutylene, isobutane and normal 20 butylene-l, all boiling below the remaining C4 hydrocarbons. This light C4 fraction may be charged to etherizer I6 while the heavier C4 fraction containing normal butane and butene-Z may be charged to alkylator I I.

The principal reaction occurring in alkylator II is the alkylation of isobutane and/or isopentane with oleilns, particularly normal butylenes, although propylene and amylenes may also be present and serve to alkylate part of the iso- 30 butane and/or isopentane.

The alkylation products are withdrawn by lin 32 and may be conducted directly by line 83 to neutraliser 2l. A part or all of vthe alkylate stream may alternatively be conducted by line 34 to scrubber 35. wherein spent acid withdrawn from I6 by line 3l is contacted with alkylate for the removal of entrained hydrocarbons and dissolved ethers. From the scrubber the alkylate 40 returns to line 33 by valved connection 31. Spent acid isWthdrawn from scrubber 3l by line Il.

lrom the neutraliser 2| the alkylate now combined with the products from etherizer Il imdergoes fractionation in debutaniser 2l and is withdrawn along with methyl tertiary butyl ether by line 39 leading to rerun tower Il wherein high boiling polymers and heavyalkylate undesired in the aviation fuel or motor gasoline are re- Mixed methyl ethers 5 moved by line 4I and the desired motor fuelprodlo uct is conducted by vapor line l! to condenser 43 and receiver M, whence the product is withdrawn by line 45. If desired, this fuel 'may be blended with other fuels and in the case of motora gasoline particularly, some butane may be added ss to increase the vapor pressure without exceeding the Reid vapor pressure specifications, generally about 9 to 12 pounds. Additional antiknock agent, particularly lead tetraethyl, may be added.

In order to prevent accumulation of normal .o

butane, propane and similar light unreacted hydrocarbons in the system, especially when' thel desired fuel is for aviation use, a part or all of the alkylate is conducted by valved line t0 are discarded by line 4l while the remaining alkylate is conducted by line Il back to alkylate line 33. If desired, alkylate may be withdrawn from the system by line I0. I'n order to avoid loss of isobutane from the system when discard-- ing normal butane by line-ll, this stock may be refractionated by means not shown and the isobutane returned to the system, preferably to alkylator Having thus described my process of making A aviation motor fuel what I claim is:

1. 'I'he process of making motor fuel from a mixture of hydrocarbon gases containing normal butylene, isobutylene and' isobutane obtained from the cracking of petroleum oils which comprises reacting said gases in an etherizing zone with methanol in the presence of sulfuric acid under conditions at which methyl tertiary butyl ether is formed from said isobutylene and methanol and normal butylene is largely unaifected, separating said methyl tertiary butyl ether from the unreacted gases, reacting the remaining gases Y containing normal butylene and isobutane in substantial amount in an alkylating zone with olefin hydrocarbons under alwlating conditions in the presence of sulfuric acid of 85 to 100 per cent concentration vwhereby said isobutane in said gases is alkylated by said olenns and transferring spent acid from said ,alkylating zone'to said etherizing zone to eilect etherization of further quantities of isobutylene therein.

2. 'Ihe process of cla-im 1 wherein the alkylation products from said alkylating zone are united with the products from said etherizing zone to produce a motor fuel of high knock rating and satisfactory volatility.

3. The process of claim 1l wherein dimethyl ether produced as a lay-product in said etherizing zone is separated from methyl tertiary butyl ether and unreacted gases and recycled to said etherizing zone.

4. 'I'he process of producing motor fuel of high knock rating which comprises alkylating isobutane in a first reaction stage with a light olen hydrocarbon imder alkylating conditions in the presence of sulfuric acid having a concentration between 85 and 100 per cent, separating the reaction mixture into an alkylatc product layer and an acid layer consisting essentially of sulfuric acid and adsorbed hydrocarbons having the effect of substantially deactivating'said acid for further alkylation, contacting said acid layer in asecond reaction ,stage under etherizing conditions with methanol and a Ci hydrocarbon mixture consisting substantially of isobutylene, normal butylene and isobutane, thereby producing a mixed methyl ether, maintaining the concenf tration of acid in said second stage within the range of 30 to 85 per cent. transferring unreacted C4 hydrocarbons. to said first reaction stage wherein said isobutanc is alkylated with said light olefin hydrocarbon, recovering said methyl ether fromsaid second reaction stage and combining it with the product of said alkylation from saidv stabilizer 41 from which propane and/or butanes es first stage to produce the desired motor fuel.

' DON R. CARMODY. 

